Passing a red light is no such success! (6)
I believe the answer is:
signal
'passing' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I can't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for signal that I've seen before include "Notable; warning sign" , "Remarkably good or bad; transmit (message)" , "Nonverbal action or gesture that encodes a message" , "Gesture, light or sound which sends a message" , "Sign that conveys a message" .)